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Running out of IP addresses?

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dpu

IS-IT--Management
Jan 24, 2005
179
US
Has anyone ever changed their subnet due to a diminishing amount of ip addresses? I currently use 24 bits of subnetting which gives me about 254 ip's. I need to dbl this so I am looking at changing my subnet to 255.255.254.0 to give me 510. I have remote locations I have to take into consideration as well which if I change to this subnet mask will affect the default gateway's of the routers. Just curious to see if anyone has had any issues doing this mid-stream besides the obvious ipconfig release & renew to get a new IP. Any advise would be great. Thanks
 
You would not need to change your gateways, but you will need to change the masks on all statically assigned devices, including your routers and switches.

Doubling is not necessarily your best option, however. Have you considered implementing multiple VLANs, that is if you have devices capable of doing so? 510 devices is a good sized broadcast domain.
 
Should be no problem as long as you get all the subnet masks changed before actually using any of the new address range. A device with a /24 mask can easily communicate with one having a /23 as long as both addresses are within the same /24.
 
Good point lgarner, I hadn't though of that. The thing dpu has to ensure, then, is that he grows his network in the correct direction. A /23 mask starts with even network and extends up through the odd, right?

If you have an existing network of 192.168.3.0, then you actually need to extend the address range *downward*, if I am not mistakenn to include 192.168.2.0, NOT upward to include 192.168.4.0, because that would be the start of another network.
 
I ran into this issue last year and as chipk suggested we went with VLANs. We made the network much more scalable and also increased efficiency. It was not terribly difficult to implement either, just time consuming after hours.

Good luck.


Matt Wray
 
Thanks for the all the advice. I have actually considered implementing a VLAN but I have never configured one nor do my current switches support it. I'm looking to upgrade to layer 3 switches but I wanted a cheaper alternative.
 
cheap slimey hack... use 192.168.0.x and 192.168.1.x with the netmask 255.255.254.0
 
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